Moldable cellulosic-derivative composition



Patented Feb. 1 1932 UNITED STATES PATENT OFFICE RICHARD L. KRAMER, OFWILMINGTON, DELAWARE, ASSIGNOB TO E. I. DU PONT DE NEMOURS & COMPANY, OFWILMINGTON,

WARE

No Drawing.

This invention relates to compositions adapted to be mass-molded intodesired articles, the base of such compositions being a cellulosicderivative, such as a cellulose ether or a cellulose ester, such ascellulose acetate or cellulose nitrate. Particularly, the inventionrelates to compositions of the char-- acter indicated which compositionswhen being molded will not adhere to the mold, and which will come fromthe mold with a Ins-- trous surface.

Heretofore, in the mass-molding of cellulosic derivative compositionsdifiiculty has been experienced because of the composition adhering tothe mold; and, furthermore, the compositions, on being removed from themold, did not have a properly lustrous surface, which necessitatedmechanical polishing of the article. I have devised a composition whichovercomes the indicated, and other, difliculties. It is a major objectof the invention to provide a composition having the advantagesindicated. To this end, and also to improve generally upon compositionsof the general character indicated, my invention consists of thefollowing matters hereinafter described and claimed.

In general accordance with the present invention, there is embodied inthe composition, prior to the molding thereof, a suitable lubricant.This lubricant prevents adherence of the composition to the mold; and,assuming,

of course, a smooth surface upon the interior of the mold, provides thatthe article when taken from the mold will have a high polish equal tothatof the mold itself. As distinguished from applying a lubricant tothe surface of the mold, the embodying of the lubricant in thecomposition avoids many difliculties due to non-uniform or incompleteapplication of lubricant to the mold, which faulty application would belikely to cause local adhesions and even failures. Also, 'flow marks,due to uneven distribution of the lubricant, are avoided.

As a specific illustration of practice in ac-' cordance with theinvention, but without restriction of the invention thereto, acomposition may be as follows:v

DELAWARE, A conromrxon or DELA- MOLDAIBLE CELLULOSIC-DEB-IVATIVECOMPOSITION Application filed October 21, 1928. Serial No. 148,800.

QParts'by weight Nitrocel1ulose11% nitrogen 20 Plasticizer-diethylphthalate 16 Fillerchina clay 62 Coloring materialnigrosine 1Lubr1cant-carnauba wax to 4 (preterred 1) In the above composition,although either hydrous or dehydrated nitrocellulose may be employed, itis to be understood that the 20 parts of nitrocellulose is to be takenas dry weight. It is to be particularly noted that compositions having,as indicated by the above formula, but a moderate amount of lubricanthave the great advantage that, despite the fact that they do not adhereto the -mold, give articles of such hardness thatthey will not showfinger printing and will have, and take, a high polish.

In the composition there may, of course, be J incorporation with anitrocellulose plastic 7 mass, but the choice is not limited to thesematerials since similar results will be obtained v in some cases withthe metallic salts of the higher saturated aliphatic acids (e. g.aluminum palmitate), paraflin, beeswax, etc., de-

pending on the filler employed, as will be understood by those skilledin the art. With regard to the filler it is pointed out that the purposeof this is to toughen the composition and to reduce shrinkage,and-filler materials of all kinds can be employed depending upon theproperties desired in the resulting composition, as will also beunderstood by those skilled in the art. So far as the particular featureof the invention is concerned, that is the incorporation of thelubricant in the composition, filler materials might be omitted from thecomposition but, so far as I am aware, such compositions would be lessvaluable in application than those containing In making the compositiona desirable procedure may consist in mixing together the variousingredients in a mixer, either with or without a volatile solvent,followed by a period of rolling on hot rolls to complete thedistribution and incorporation of all ina gredients, insure a uniformintimate mixture,

and eliminate all volatile matter. The resulting product is then sheetedfrom the rolls and ground in a suitable grinderto reduce it to a powder.When thus powdered, the composi-' tion is in proper form for molding. Aswill be understood by those familiar with massmolding, the compositionis introduced into the (metal) mold and molded under heat and pressurein the usual way, the presence of the lubricant in'the compositionintroducing no complications into the molding operations.

While, for the sake of definiteness of description, more particularreference has been made to nitrocellulose, it is to be understood thatother cellulosic derivatives, such as cellulose acetate and celluloseether mayform the base of compositions containing lubricant in generalaccordance with the invention.

I claim:

As a mass-molding powder, a granulated intimate mixture comprising acellulose derivative, a meltable mold lubricant of the class consistingof carnauba wax, candelilla, or ceresine wax, aluminum palmitate,paraffin and beeswax, in quantity insufficient to substantially efl'ectthe hardness of the surface of the molded article, and a filler inquantity suflicient to substantially counteract shrinkage of the massduring molding.

In testimony whereof I aflix my signature.

RICHARD L. KRAMER.

